Rounds counter for automatic firearms



July 18,1944. G. WEBB ROUNDS COUNTER FOR AUTOMATIC FIREARMS Filed Sept. 27, 1941 2 Sheets-Sheet l J27 1/5212 01" E 011175 Webb A725 t arngy July 18,1944. 6. WEBB ROUNDS COUNTER FOR AUTOMATIC FIREARMS Filed Sept. 27, 1941 2 Sheets-Sheet 2 arn y Patented July 18, 1944 ROUNDS COUNTER FOR AUTOMATIC FIREARMS George Webb, Hartford, Conn., assignor to Colts Patent Fire Arms Manufacturing Company, Hartford, Conn, a corporation of Connecticut Application September 27, 1941, Serial No. 412,565

5,. Claims.

This invention relates to a mechanism for counting and registering the number of rounds of ammunition fired by an automatic firearm.

One of the objects of the invention is to provide mechanism for actuating with certainty a counter and register through the medium of certain movable parts of the firearm. Another object of the invention is to provide means to actuate an electrically operated counter and register, the actuating means being so designed that nornal vibration or jarring of the gun will not ac- :identally operate the counter to register a false :ount.

A still further object of the invention is to Jrovide a switch adapted to be opened and closed :y the movement of the barrel extension of an iutomatic firearm, the closing of the switch acuating a counter for indicating the number of 'ounds fired by the firearm. The construction s such that the switch is held closed to actuate .he counter during the major portion of the cycle if movement of the barrel extension and that the :witch is positively held in open position while he firing of the shell or cartridge occurs whereby he extreme vibration imposed upon the entire ire'arm due to such firing will in no way jar the Witch closed before its normal time for closing.

Other objects of the invention will be apparent mm the study of the specification and drawings vhich form a part thereof.

The accompanying drawings show the embdinent of the invention which is deemed preferable, ut it Will be understood that the drawings are otended for illustrative purposes only and are [0t to be construed as defining or limiting the cope of the invention, the claims forming a part f this specification being relied upon for that 'urpose.

In the drawings,

Fig. 1 is a fragmentary view of the breech cas- 1g and certain associated parts of an automatic rearm shown in side elevation with a switch lounted thereon, the switch being in open posiion and the barrel extension being forward in ring position.

Fig. 2 is a view similar toFig. 1 showing the arrel extension retracted sufiiciently to permit 1e switch to close.

Fig. 3 is an end elevation of the switch per se ith the casing partly broken away to expose )mponent parts of the switch.

Fig. 4 is a sectional side elevation of the switch [ember mounted on the firearm, only those parts i the firearm adjoining the switch being illustrated, the latter being in dot-and-dash lines; and

Fig. 5 is a diagram of the electric circuit connecting the component parts forming the instant invention.

The structure of the present invention, for purposes of convenience, has been illustrated in connection with a 37 mm. automatic firearm, the details of which firearm in general are fully set forth in applicants co-pending application Serial No. 325,405 filed March 22, 1940. Said co-pending application also is based on and refers to U. S. Patent 1,525,065 to Browning, dated February 3, 1925, to which attention is also directed. The instant illustration, however, is in no way to be considered restrictive but merely illustrative since the details of the invention may be readily applied to other types of automatic firearms and function in the manner contemplated in connection with the present illustration.

In certain uses of automatic firearms as on aircraft, for example, it is diflicult for the gunner to ascertain how many rounds of ammunition have been fired and similarly the number of rounds remaining in the magazine to be fired. The instant invention, while applicable to numerous types of automatic firearms, has been found particularly useful in connection with automatic firearms wherein the number of rounds of ammunition usually carried by the magazine is limited and it is quite vital for the gunner to know especially how many rounds of ammunition remain to be fired.

In aircraft, the firearm is frequently mounted in positions remote from the gunners compartment whereby it is impossible for the gunner to see the magazine or reload the same in flight. Upon the magazine becoming exhausted of shells or cartridges, the gunner must return to a base for reloading of the magazine. Also, since enclosed magazines are generally used on the types of automatic firearms with which the use of the instant invention is contemplated, it is substantially impossible for the gunner to ascertain the number of shells or cartridges remaining in the magazine even if he could see the magazine. Furthermore, as it is essential for the gunner to know the number of rounds of ammunition remaining in his magazine before engaging in battle under the circumstances described above, the instant invention has been developed to provide a counter and register mechanism and means to actuate the same whereby the gunner may be furnished with the accurate desired information. Previous attempts have been made to provide on the top plate of the breech casing of an auto?- matic firearm with an actuating means-for the switch extending through a suitable aperture in said top plate. The barrel extension of the fire:

arm is provided with a cam groove with which the actuating means for the switch coacts to open and close the switch as the barrel extension moves backward and forward in recoil and counter-recoil movement. The switch is connected in a circuit including electric power source and counter mechanism for indicating the number of rounds of ammunitionfired. The counter mechanism may be mounted in any convenient position such as on the instrument panel of an airplane or even on the location.

In the present illustration the switch has been placed on the top plate of the breech casing just forward of the feed box adjacent one side of the breech casing as the preferred location. It is to be understoodthat the illustrated location of; the switch and cam groove in the barrel extension may be changedand said switchand cam groove may be placed in any other convenient location on the firearm wherein the principles of the invention may be carried outwithin the spirit contemplated, all of which are described herein.

In the drawings, a fragmentary portion of the breech casing I is shown with a part of a feed firearm in any convenient box I2 mountedon-the top thereof, Various parts of the operating mechanism of the firearm are shown depending below the breech casing, all of which mechanism is explained in detail in said co-pending application and patent. Further description of details of the operation of the firearm vproper will not be made in this application since the same does, not form an integral part of; the present invention other than the operation of the parts of said firearm immediately associated with the elements comprising the instant invention. For a detailed descriptionof the operation of such additional illustrated mechanism, attention is invited to said co-pending application and patent.

A barrel extension I4 is movable in a reciprocating manner within the breech casing by the firing of the firearm due to the recoil and counterrecoil forces imposed upon the barrel extension.

A longitudinally extendin groove [6 is'provided in the upper surface of said barrel extension near the forward end thereof, the bottom of the groove being parallel to the top of the barrel extension for part of its length and then curving upward to meet the upper surface of the barrel extension aswell illustrated in Figs. 1, 2iand4. A switch It ismounted on the top plate 2llof the breech casing. The switch consists of a casing 22 having an electrical conduit inlet bushing 24 mounted in the forward wall thereof. The bushing 24 is preferably externally threaded to accommodate a coupling for said electrical conduit. A base plate 26 on the switch is secured to the top ing 22 issecured to the base plate by a screw 30.

plate 20 bymeans of a suitable screw 28. The cas- A plurality of insulation block 32 and 34 are secured to the upper wall of the casin by screws i the insulating block 34- by rivets 40, one end of each of said conductors having contact members 42 secured thereto The rivets are insulated from the casing 22 by insulation block 32. Screws 44 are also threaded into the respective conductors to secure the wires of the electric circuit to the respective conductors.

Vertically disposed in an aperture 46 in the base plate is a bushing 48, preferably formed of bronze, in which amovable means illustrated as a plunger 50 is disposed for free vertical sliding movement, the plunger 50 having a rounded lower end, Said plunger has an annular flange portion 52 formed thereon intermediate of its length and a collar 54 is riveted onto a reduced portion 55 formed on the upper end of the plunger. An insulating block 58 having an aperture 60 to receive the plunger 50 ismounted on the plunger between the collar 54 and the flange 52 for vertical movement with the plunger. The collar 54 isspaced from the flange 52 a greater distance than thet hickness of the insulating block 58 whereby a limited amount of vertical movement of the insulating block is permitted on the plunger 50.

Riveted or otherwise suitably secured to the insulating' block 518 is a U-shaped' metallic bar 62 having contact members 64 disposedat opposite ends thereof. Said contacts are adapted to respectively engage the contacts 42 for effecting a closed circuit between the ends of the electric circuit wires, disposed in the switch casing. A coiled helical Spring 66 surrounds the collar 54, whicl spring is sufficiently long to extend upward t engage the upper inside surface of the casing 21 to normally exert pressure downward on the insulating block 58, whereby the bar v62 carries thr contacts 64 into circuitclosing relationship witl the contacts 42.

The top plate 20 of the breech casing is alsl provided with aesuitabl e opening or aperture 6. to freely accommodate, the bushing 48 and plung er 55, the lower end of the plunger normally ex tending below the underside of thetop plate 20 substantial 'amounta'sshown in Figs. 2 and 4.

The counter 68, which is electrically operate: is of conventional design and construction, bein the type that registers-a count each time the on cuit in which the counteris connected is closer The counter 68 is connected in series in th circuit by 'conventional wiring 69,'shown in-Fi'g. 1 with a suitable electric power source To which he been illustrated in said figure as aconve'ntion: battery. It is to be understood that this powe source, however, may be any other satisfactoi equivalent such as a generator or current from power line, for example. The switch' 18 is die grammatically shown also connected in series 1' the circuit shown in Fig. 5. V. l

,As an example of the cycle of operation of ti applicants constructiomassume the barrel 'e: tension is in its forward position in the bree casing and the switch is held open by the plung 50 which is pressed upward by the barrel extei sion ,as shown inFig. 1.. The cartridge. or shr is then fired. Immediately upon t-hefiring of t] shell orcartridge, the barrel extension is quick moved toward the rear 'of the breech casing by ti recoil action of the firearm, during which mov groove 16 until the contacts Hand 42 comein engagement with each other through the action of spring 66 forcing downward the plunger 50 which carries contacts 64. The engagement of said contacts will thus close the circuit and effect another actuation of the counter for the firing which has just taken place. The contacts will remain in circuit closing relationship during the majority of the cycle of movement of the barrel extension, thus insuring a certain actuation of the counter and preventing the possibility of a false actuation of said counter which might occur in the case where the circuit was closed only for a very brief interval during the cycle of movement of the member which closed the switch. The spring 66 is sulficiently strong to prevent vibrations imposed upon the firearm from accidentally opening the switch while the barrel extension is in retracted position and out of contact with the lower end of the plunger 50.

When counter-recoil movement of the barrel extension takes place, the bottom of groove I6 will engage the lower end of plunger 59, near the end of the forward movement of the barrel extension, to force the plunger upward and open the circuit by moving contacts 64 away from contacts 42.

The switch is thus held open with certainty, in circuit breaking position, while the cartridge or shell in the firearm is actually being fired. This is the occasion when the maximum amount of vibration is imposed upon the entire firearm and any mechanism carried thereby. There is therefore no possibility of the switch accidentally closing while such maximum vibration occurs, thus insuring accuracy in the operation of the counter connected in the circuit of the device during all phases of operation of the structures.

While the invention has been illustrated and described in its preferred embodiment and has included certain details, it is to be understood that the invention is not to be limited to the precise details herein illustrated and described since the same may be carried out in other ways, fallin within the scope of the invention as claimed.

What I claim is:

1. The combination of an automatic firearm including means movable upon each firing of said firearm. an electrically actuated counter, an electric power source, a switch, a circuit connecting said counter, electric power source and switch, and means actuated by said movable means upon movement thereof to operate said switch and open and close said circuit to actuate said counter, said switch operating means holding the switch open at the time of firing said firearm.

2'. The combination of an automatic firearm including means movable upon each firing of the firearm, an electric switch mounted on said firearm, an electrically actuated counter, an electric power source, a circuit connecting said switch, counter and electric power source, and

means freely biased in one direction and actuated by said movable means upon movement thereof to operate said switch and open and close said circuit to actuate said counter to register each firing of said firearm, said switch operating means holding the switch open at the time of firing said firearm.

3. The combination of an automatic firearm including a breech casing having a member movable therein upon each firing of the firearm, an electric switch mounted on said firearm, an electrically actuated counter, an electric power source, a circuit connecting said switch, counter mechanism, and power source, and means freely biased in one direction and actuated by said movable member upon movement thereof to operate said'switch and open and close said circuit to actuate said counter and register each firin of said firearm, said biased means holding said switch open at the time of firing said firearm.

4; The combination of an automatic firearm including a breech casing having a barrel extension provided with a cam surface and movable in said breech casing upon each firing of the firearm, an electric switch mounted on said breech casing, an electrically actuated counter, an electric power source, a circuit connecting said switch, counter, and electric power source, and means freely biased in one direction and engageable by said cam surface on said barrel extension for actuation thereby upon movement thereof to operate said switch and open and close said circuit, to actuate said counter and register each firing of said firearm, said barrel extension and last mentioned means holding said switch open at the time of firing said firearm.

5. The combination of an automatic firearm including a breech casing having an opening therethrough and a member provided with a cam surface and movable in the breech casin upon each firing of said firearm, an electric switch mounted on said breech casing, a switch actuating member projecting and freely movable through said opening in said breech casing and also engageable with the cam surface of said member, means normally biasing said actuating member toward switch closing position, an electrically actuated counter, an electric power source, and a circuit connecting said switch, counter and electric power source, said cam surface on said member engaging said switch actuating member at the time of firing of the firearm to maintain said switch in open position to break the circuit and said cam surface also being movable with said member to release said switch actuating member following the firing of the firearm to permit closing of said switch and circuit to actuate the counter and register each firing of the firearm.

GEORGE WEBB. 

